I had recently repaired - modified a YPVS control unit and also made a custom SDR200 leak down tester tool for Matthew(UK). The Sdr200 is a unique bike with a Trellis frame. The YPVS exhaust valve curve is also unique to this model.

I just repaired a YPVS unit for a Yamaha DT200R 37F bike, that belongs to Tony(UK) and I have another one rare YPVS curve to share. This unit doesn't seem to use the regular DT200 ypvs curve but instead uses the one below.

A recent modification on a '98-'99 Cr125 bike that alters the exhaust valve timing. A simple spacer made on the metal lathe that adds some preload on the governor spring hence retarding the engagement with the exhaust valve linkage. This mod can help for enduro use or with bigger carbs.
I mostly followed the instructions from the below link though I made the spacer slightly thinner at 2mm thick.
Link at : Honda 125 - HPP setup TIPS & TRICKS & TUNING @ thumpertalk.com